Nur eine Instanz einer .Net Anwendung

Diese Klasse hilft einen Anwendung nur einmal zu starten.

Der Code prüft ob bereits einen Instanz der Anwendung läuft und bringt diese dann auf Wunsch in den Vordergrund. Die neu gestartete Instanz kann dann über Application.Exit() beendet werden.

Hinweis: Fenster die minimiert oder unsichtbar sind werden nicht in den Fordergrund gebracht. Hier ist die Implementierung der APIAufrufe "GetWindowPlacement" und "SetWindowPlacement" erforderlich.

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 1 using System;
 2 using System.Windows.Forms;
 3 using System.Runtime.InteropServices;
 4 
 5 
 6 namespace Toolbox
 7 {
 8     /// <summary>
 9     /// This class helps to create a Application which allowed onyl on instance (like word, excel, eg)
10     /// </summary>
11     internal abstract class SingleInstanceManager
12     {
13         //TODO: create your own GUID with GuidGen!!!
14         private const string APPID="{AD0C0725-18BE-4eaa-8FE6-17F0FC14A971}";
15 
16         #region Win32API
17         [DllImport("user32.dll")]
18         private static extern long BringWindowToTop(long hwnd);
19 
20         [DllImport("user32.dll")]
21         private static extern long SetForegroundWindow(long hwnd);
22         #endregion
23 
24         #region Worker
25 
26         /// <summary>
27         /// check whether an other instance of the current application is running
28         /// </summary>
29         /// <returns>
30         /// true if you can start a new instance, 
31         /// false if an instance is running
32         /// </returns>
33         public static bool StartNewApplication()
34         {
35             return StartNewApplication(false);
36         }
37 
38         /// <summary>
39         /// check whether an other instance of the current application is running
40         /// </summary>
41         /// <param name="BringToTop">
42         /// true: the other instance will shown
43         /// false: the other instance will not shown
44         /// </param>
45         /// <returns>
46         /// true if you can start a new instance, 
47         /// false if an instance is running
48         /// </returns>
49         public static bool StartNewApplication(bool BringToTop)
50         {
51             bool retVal = true;
52             System.Threading.Mutex mu = new System.Threading.Mutex(false, APPID);
53 
54             if (mu.WaitOne(0, false) == true)
55             {
56                 //start a new one
57                 retVal = true;
58             }
59             else
60             {
61                 //an instance is running
62                 retVal = false;
63 
64                 if (BringToTop)
65                 {
66                     foreach (System.Diagnostics.Process p in System.Diagnostics.Process.GetProcessesByName(System.Diagnostics.Process.GetCurrentProcess().ProcessName))
67                     {
68                         if (p.Id != System.Diagnostics.Process.GetCurrentProcess().Id)
69                         {
70                             //p.MainWindowHandle;
71                             SetForegroundWindow(p.MainWindowHandle.ToInt64());
72                             BringWindowToTop(p.MainWindowHandle.ToInt64());
73                         }
74                     }
75                 }//end BringToTop
76 
77             }//end Running ?
78             return retVal;
79         }
80         #endregion
81     }
82 }
83